DE1495714A1 - Process for producing melts of high molecular weight polyamides with particularly high stability - Google Patents

Description

to our submission from ₄ . June 1968

FARBENFABRIKEN BAYER AG

LEVERKUS EN-Bayerwerk patent department S d t / j θ

Process for the production of melts of high molecular weight polyamides with particularly high stability

High molecular weight linear polyamides, e.g. As poly - ^ - caprolactam etc. lactam and adipamide, are suitable because of their excellent chemical resistance, and because of the excellent mechanical properties of the moldings for a variety of technical purposes. If these polyamides are deformed via the melt flow, they form extremely thin melts and, because of the resulting low melt level, are not very suitable for the production of profiles, pipes, deep-drawn parts and, in particular, blown bodies.

It has already been proposed to increase the viscosity of the polyamide melts by adding crosslinking agents which are able to react with the reactive hydrogen atoms. As a crosslinking agent, for. B. epoxy resins, low molecular weight compounds containing epoxy groups and isocyanates are possible. Suitable compounds of this type are, for. B. di- or polyepoxides of mono- or polybasic amines, e.g. B. N-di (2,3-epoxypropyl) -

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splitting off aniline, hexamethylene diisocyanate or isocyanates Substances such as the adduct of 2 moles of phenol or 2 moles of • Caprolaetam and a ?? » Moles of hexamethylene diisocyanate.

Good results are also obtained with dioxylenes from dioyclohexenylalkanes in amounts of about 0.5 to about 1.5 percent by weight in the case of polyamides of normal molecular weight, d. H. with molecular weights of about 20-30,000, correspondingly a relative viscosity in 1 solution in m-cresol

P from about 2.3 to about 2.6 at 25 ° C. The more Epoxides are added to these polyamides, the higher the viscosity of the melts. That way you can useful polyamides can be made with a relative viscosity of up to about 4.0. Such polyamides can be processed quite well on the usual screw presses, but their melts are special for the manufacture of blown bodies un; certain semi-finished products still not sufficiently stable. A further increase in viscosity and stability by adding larger ones Amounts of epoxides e.g. B. 2 percent by weight, does not achieve the goal, because the melts then rubber-elastic will. As a result of the high restoring forces of such melts conveying difficulties occur in the extruder, leading to irregular output and imprecise dosing and thus lead to inferior molded parts.

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P 14 95.714.3 ^ Appendix to our entry

\ & dated June 4, 1968

It is also already known by polymerizing in the melt or by Mach condensing in the solid state Polyamides with increased molecular weight, for example more than 30,000, corresponding to a relative Viscosity in excess of about 4.0, which results in higher melt viscosity and improved melt level exhibit. However, these products are only suitable to a limited extent for the manufacture of profiles, pipes, blow moldings and deep-drawn parts. Leave in the blow molding process only hollow bodies with a content of up to about 2 liters can be preserved reasonably satisfactorily. For blown bodies However, this size already makes clear that these products are still inadequate noticeable. Pie inflatable bodies have an uneven wall thickness and tend to warp. Larger containers cannot be produced at all. Made from this material Plates show a strong tendency when they heat up to sag and are therefore suitable for the deep-drawing process not suitable. Rods can only be produced reasonably satisfactorily from this material in diameters of aenr than about 20 mm.

It has now been found that for the production of profile parts, Pipes, deep-drawn parts and blown bodies with extremely suitable high-molecular-weight polyamides

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BATH

P 14 95.714.3 Appendix to our submission

*, dated June 4, 1968

high melt viscosity and particularly high melt stani can be obtained by polyamides having a molecular weight of at least about 40,000, preferably about 50,000 to about 60,000, crosslinking agent added,

The polyamide melts produced according to the invention offer in contrast to the known crosslinked melts produced from polyamides of lower molecular weight im

t Extruder no. conveying difficulties, but occur evenly and quickly from the extruder and can therefore be dosed perfectly. Since they, surprisingly Despite their high stability, they do not show any rubber-elastic behavior without difficulties can also be deformed into large objects. For example, extrusion gives one Melting hose of high stability, which can be effortlessly inflated in a suitable shape and made into hollow bodies even wall thickness deform IaSt, which do not

'more prone to warp. It is for example possible, after the blow molding hollow body up to about 60 1 content, z. B. bottles, fuel tanks as well as to manufacture containers of all kinds. Furthermore, the material can be made into plates of without difficulty For example, process 1 mm thickness, which by deep drawing can be perfectly formed into molded bodies with good lateral

909827/1509

P 14 95.714.3 Appendix to our submission

r "* dated June 4, 1968

1 * 95714

stiffness can be deformed. Even void-free rods with a diameter of 10 mm, for example, can pass through Extrude can be produced flawlessly.

The amounts of the crosslinking agents mentioned to be expediently added to the melts can be varied within wide limits vary and are essentially dependent on the type of polyamide used and the properties to be achieved of the end products. They can easily be determined from case to pail by means of simple experiments. In general Additions of about 0.1 to about 2 percent by weight are sufficient. Larger amounts increase the melt viscosity of the As a rule, polyamides are no longer essential, entirely in the In contrast to polyamides, normal molecular weight. The crosslinking agents can in a conventional manner with the Polyamides are mixed, e.g. B. by adding to the molten or dissolved plastics before, during or after their manufacture. It is particularly advantageous to combine polyamide granules well with the crosslinking agents mix and then continuously melt for a short time, z. B. according to the method of German patent 1 027 398.

Other crosslinking agents can also be used with the linear polymers other substances are added, including their properties to modify. May be mentioned e.g. B. anti-aging agents, pigments, dyes, metal powders, fillers, plasticizers Resins and other plastic natural products, crystals;

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P 14 95 <714.3 Annex to our entry

from June 4, 1968 ν

germs, mold release agents, etc., 1495714

Example 1:

20 kg of granules of a polyamide 6 of molecular weight 50,000 are two hours with 120 g of Oi- (3> 4-epoxy) -cyclohexenyl-dichloromethane mixed on a vortex roller and through an extruder with a single three-zone screw homogenized as a bristle, peeled off, chopped and dried

a) The granules obtained are melted in an extruder and extruded through an annular nozzle, a Schruelzschlauch, der, from a blow mold is obtained added, is deformed with compressed air to a container of 20 1 content.

b) From the above granules in an extruder with a slot die Manufactured panels of 0.5-3 mm thickness are cut into pieces of suitable size, on softened in a thermoforming device with hot air and after Vacuum opening on a male mold to a cylindrical one Deformed container.

c) From which it is melted in an extruder and through a suitable nozzle into a calibration device Cooling extruded granules gets r: ian ο no trouble Void-free rods of less than 10 ram cross-section according to the usual continuous and discontinuous Production method. BATH ORIGINAL

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P 14 95.714.3 ψ> Appendix to our entry

¹ dated June 4, 1968

Example 2:

As indicated in Example 1, 20 kg of pure granules are obtained from polyamide 6 with a molecular weight of 50,000 two hours with 120 g of di- (3 »4-epoxy) -cyclohexenyl-dimethylmethane mixed on a spin roller. These granules are then melted using an extruder and. extruded through an annular nozzle. As in Example 1, a melting tube is obtained which is that described there Way can be deformed to a container of 20 1 content.

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Claims (1)

Jl. -m P 14 95. 914.3 Appendix to our entry ι dated June 4, 1968) Claim: ' ^{öö /} ' *. ,,. " A method of producing melt high molecular weight polyamides having a particularly high stability, characterized in that the ^v polyamide having a molecular weight of at least about 40,000, preferably about 50 000 to about 60 000 in the form of its granules with 0.1 to 2 weight percent, based on the polyamide, mixed with a crosslinking agent and then briefly melted. New UnterfaOen (Art 7 i 1 Ab ^ 2 No. 1 Setz 3 des Xnderung ^ M. Y. 4.8.] JMQ Ue 20 99 - 8 909827/1509